NTA ASTM Testing Standards: Provides a reference standard that compares 4 known types of Chinese drywall to US drywall in terms of hardness, nail pull resistance and flexural strength. See http://www.ntainc.com/test/Gypsum-board-testing.htm for more information on theseprocedures.

Centek Labs Sulfur Emission Standards: Provides a reference standard that compares 4 known types of Chinese drywall to US drywall using Centek's headspace analysis for sulfur gases. For more information on this procedure see: http://www.centeklabs.com/index.htm